Joseph Gordon-Levitt travelled to Russia to meet Edward Snowden before playing him on camera.

Joseph - whose visits were arranged by Snowden's attorneys in the US and Russia, where he lives in exile - shared: "A few months before shooting the movie, I did have a chance to sit with him in person.

"It was honestly not as crazy as you would imagine.

"I flew to Moscow and went and met him at an office."

Joseph, who stars in the movie alongside Shailene Woodley, admitted he relished the chance to study Snowden in person and learn more about his character.

He told People: "One of the first things I noticed actually was, he's got really good manners.

"He's sort of old-fashioned, in a way. You don't necessarily expect that in today's world, or when you think of someone who's really good at computers.

"You don't necessarily equate that with someone who's got a lot of social grace. But what can I say? He's from North Carolina.

"I think they put a lot more emphasis on good manners there than they do where I'm from in Southern California. I really noticed that. I wanted to incorporate it into my performance of him."

Snowden, meanwhile, previously appeared in the Academy Award-winning documentary 'Citizenfour', although he insisted he had no commercial interest in the film.